A fragment comprising the last third of bovine serum albumin which accounts for almost all the antigenic reactivity of the native protein.

摘要: The fragmentation of native bovine serum albumin by trypsin has been studied in aqueous solution under various conditions with regard to the yield and size fragments obtained. From a partial tryptic hydrolysate at pH 8.2 (40 degrees, 1 hour), homogeneous fragment was isolated high gel filtration on Sephadex G-100, followed chromatography DEAE-cellulose. molecular weight calibrated G-100 columns sodium dodecyl sulfate electrophoresis 22,500. After reduction disulfide bonds alkylation resultant thiol groups iodoacetamide, retained homogeneity disc its remained unchanged, indicating that it composed single polypeptide chain. amino acid composition, sequence first 20 residues, actions carboxypeptidases A or B, unequivocally assigned positions 377-571 albumin. inhibitory activity 90 93% towards immune reaction protein IgG fraction antisera. IgGfraction accounted for 96% total antibody An immunoabsorbent removed 89 95% fluorescent derivative fragment, which full immunochemical activity, found bind 2 mol antibody/mol peptide. disulfides peptide were essential because latter entirely abolished upon S-alkylation disulfides. Since this comprised only third molecule, but antigenic reactivity, results indicated carries identical repeating reactive sites.